3 frequency methods

[Grumpy]

I am starting this topic for those following the 3-frequency method.

The XR2206 is cool, but for rock-solid adjustable frequencies - I recommend the Vackar VFO (variable frequency oscillator) - also known as the Tesla oscillator - I have no idea why it is called this.

Anyway, the Vackar circuit is absolutely rock solid - one of the best ever devised.  Developed by Jiri Vackar in the 40's.  This will easily get you into the mhz range and keep you there.

http://www.pan-tex.net/usr/r/receivers/elrvfo.htm#history
www.qsl.net/va3diw/vackar.html
www.pan-tex.net/usr/r/receivers/elrvfo.htm

If you are using pulses - don't bother with this - you don't need it, but it is pretty nice if you ever need a VFO.

[starcruiser]

I'll need to checkt this out. BTW, it was stated prior in the original SM thread that pulses of 10uS or less is what is required. If we take this number and work it out we find that a squarewave of 50Khz would put us at 20uS (half of that is of course 10uS).


      1               1
f=  ---   or  t= -----
      t                f


I have noted while testing that when the frequency is above this point reducing the pulse width does not seem to show any improvement in signal output.

We do require multiple signal sources that are adjustable (able to finely adjust the frequency) so we can determine the sweet spot for the 3 frequencies.

Just my .02

[Grumpy]

10uS or less

I have pointed that out a few times.

You need to take into account the flow of charge in the conductor - nothing near light speed - related to the level of current.  Small current = low speed charge flow, high current = high speed charge flow. 

For comparison, the speed of current flow in a normal 100w, 120vac lamp is something like 3 inches an hour.

According to Tesla, reducing the pulse width to below 100 ns prodused cold electricity and pretty lighting effects.  the three things that Tesla identified as relavent are voltage, pulse width, and no reversal of current.

Look at all of the ringing you get with the 3-freaks method - signal doesn't know wether to crap or go blind.

I have noted while testing that when the frequency is above this point reducing the pulse width does not seem to show any improvement in signal output.

- increase the "pulse repitition rate" and/or voltage level.

While I'm on the keyboard, there is but one field that could come out of that wire - perpendicular to it - when the flow is suddenly halted.  This particular field could give a crap less about conservation, as it is not conservative.

[Grumpy]

XR2206:

source in US: http://www.unicornelectronics.com/IC/EXAR.html
(Also Jameco carries them.)

Exar also makes an XR2207 and XR2209. 

See some examples and datasheets below:

[Grumpy]

Really in the zone today.  Been thinking about the cryptic reference to "3-frequencies" and remembered something about harmonics in waveshaping circuits.

Looking into this, I find that waveshaping circuits combine the fundamental frequency with the harmonics to create the waveshape that is desired. 

For example, a squarewave may theoretically have an infinite number of only odd-order harmonics.

In the peaked wave, harmonics such as the third, seventh, and so forth, cross the reference line 180 degrees out of phase with the fundamental; the fifth, ninth, and so forth, cross the reference line in phase with the fundamental. So, not just any old harmonic will do!

Sawtoothed waves are comprised of odd and even such as the fundamental, 2nd and third on up to 30th or more depending on the shape - ringing all the way.

Very interesting.  I'm thinking that synthesized waveforms may not be up to the task.  Not that it will not work, just not the direct route.